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What is Heterobilharzia americana? US experts raise alarm over dog-killing parasite found in Colorado River
In a first, Southern California discovered a dog-killing flatworm parasite in the Colorado River as scientists warn of its spread in other states.
In a first, Southern California discovered a dog-killing flatworm parasite in the Colorado River as scientists warn of its spread in other states.
According to a study conducted by the University of California, Riverside, the parasite, known as Heterobilharzia americana was once found primarily in Texas and other Gulf states, is a flatworm also called a liver fluke. It has now migrated to the west.
The worm can cause canine schistosomiasis, which affects dogs' livers and intestines. While there are therapeutic options for dogs who become infected, experts say such treatments are not always effective, and infections may lead to euthanasia.
"Dogs can die from this infection, so we are hoping to raise public awareness that it’s there," UC Riverside nematology professor Adler Dillman told the UC Riverside News. "If you’re swimming in the Colorado River with them, your pets are in peril."
A look at the research findings
As the virus typically spread by snails, the researchers gathered over 2,000 snails from the Colorado River's banks and tested DNA to determine the presence of snails and flatworms.
The researchers were shocked to discover that two types of snails can transmit the parasite. “Not only was it a surprise to find H. americana, we also did not know that the snails were present here," Dillman stated in a statement.
Other than dogs, the parasite can infect other species, including raccoons, marsh bunnies, horses, mountain lions, and opossums.
The parasite first enters epidermis and then moves to the lungs, where it can cause hemorrhage.
“The presence of the adults in the veins isn’t the problem. It’s the eggs that get into the lungs, spleen, liver, and heart. The immune system tries to deal with it, and hard clusters of immune cells called granulomas form. Eventually, the organ tissues stop functioning," Dillman told UC Riverside News.
According to UC Riverside News, 11 dogs contracted the infection in California counties and one of them has died since 2019.
Symptoms and treatment: Can parasite cause infection in humans?
Emily Beeler, a veterinarian with the Los Angeles County Department of Public Health, stated symptoms that typically appear gradually include lack of appetite, vomiting, diarrhea, significant weight loss, and signs of liver damage.
Beeler advised that if any dog shows these symptoms then one should ask veterinarian for a simple fecal test. A veterinarian would use multiple medications to treat the dog by keeping the pet under close monitoring.
The parasite is ineffective of triggering such an infection in humans. Experts have warned dog owners to be cautious and aware while taking their dogs for swimming in rivers and wetlands.
